checkpoints

Turn a finished Halo training run into a usable artifact, and resume correctly. USER-INVOKED ONLY. Use when the user asks to "merge EP shards", "load my EP/MoE checkpoint into vLLM", "merge a LoRA/QLoRA adapter", "convert to bf16", "quantize to fp8/fp4", "reset GptOss sinks", "unfuse MoE experts", "merge several checkpoints into one", or "resume from a checkpoint" — anything about checkpoint format, the…